A gay New Jersey couple is suing a national anti-LGBT rights organization after a photo of their engagement party was altered and used in mailers opposing same sex marriage in Colorado.

Brian Edwards and Tom Privitere discovered that the photo of them kissing in front of the New York City skyline had been modified to make them appear as if they were in snowy Colorado and was used by the group Public Advocate of the United States to attack Colorado state Sen. Jean White (R).

Wording placed over the photo read, "State Senator Jean White’s idea of 'Family Values?'"

That's when the couple contacted the Southern Poverty Law Center, which lists Public Advocate as a hate group.

"We are heartbroken that our images may have been seen by gay and lesbian youth in Colorado and were left feeling ashamed of their sexual orientation because of it," Privitere said in a statement. "We hope that this group is held accountable for its reprehensible and hateful anti-gay attacks."

The SPLC on Wednesday filed suit in federal court for the District of Colorado on behalf of Edwards, Privitere and photographer Kristina Hill of Kristina Hill Photography. They asked the court to award damages, costs and attorneys fees for theft of the photo.

"This case is about the defilement of a beautiful moment by a group known for demonizing the lesbian, gay, bisexual and transgender community," SPLC deputy legal director Christine Sun said. "This was just a cheap way for Public Advocate to avoid having to pay for a stock photo to use in their hateful anti-gay attack ad. It was nothing short of theft."

The couple believes that the photo was stolen after they shared it with friends and family on their blog.

"I cringe every time I look at what once was one of our favorite photos," Edwards explained. “All I see now is the defiled image used to attack our family and our community. All we want is justice for the pain that Public Advocate has caused us.”

According to the SPLC, Public Advocate has a history of attacking the LGBT community. One fundraising letter implored readers to "imagine a world where the police allow homosexual adults to rape young boys in the streets." The group also once staged a "Man-Donkey Mock Wedding Ceremony."

Watch this video from ABC News, broadcast Sept. 26, 2012.

Unfortunately your browser does not support IFrames.

(h/t: ABC News)